1. Field of the Invention
The present invention relates to an improved variable venturi carburetor, which is part of an intake system of an internal combustion engine. More particularly, the present invention relates to structural features of the carburetor, which allow an air intake path of the carburetor to be shortened, and which allow the size of upper air chambers of the carburetor to be reduced.
2. Description of the Background Art
Variable venturi carburetors are known. For example, Japanese Utility Model Application No. SHO 64-7235 discloses a variable venturi carburetor.
In the variable venturi carburetor of the background art, a piston valve of the carburetor is formed as a hollow cylindrical body. A diameter of the piston valve is larger than an internal diameter of the venturi. Therefore, the piston valve occupies a large portion of the intake path of the carburetor. As a result, the intake path must be made relatively long. Further, a flange at the upper end of the piston valve, which is used to connect a diaphragm to the piston valve, must have a relatively large diameter. Accordingly, the diaphragm coupled the flange is large in diameter. The large diaphragm requires that large upper air chambers be formed on the carburetor.